JP2022156218A - Polyamide composition and molded body - Google Patents

Abstract

To provide: a polyamide composition from which a molded body with improved limit PV value and impact resistance can be obtained; a molded body using the polyamide composition; and a method for improving the limit PV value and the impact resistance of a slide member.SOLUTION: A polyamide composition comprises a polyamide, an olefinic elastomer, and an ethylene-styrene graft copolymer. A molded body is formed by molding the polyamide composition and has Rockwell hardness measured in M scale according to ISO 2039-2:1987 of more than 50 and less than 80. A method for improving a limit PV value and impact resistance of a slide member includes obtaining the slide member by molding the polyamide composition comprising a polyamide, an olefinic elastomer, and an ethylene-styrene graft copolymer. The Rockwell hardness of the slide member measured by M scale according to ISO 2039-2 is more than 50 and less than 80.SELECTED DRAWING: None

Description

The present invention relates to polyamide compositions and moldings.

Polyamides represented by polyamide 6 (hereinafter sometimes abbreviated as "PA6") and polyamide 66 (hereinafter sometimes abbreviated as "PA66") are excellent in moldability, mechanical properties or chemical resistance. Because of its excellent properties, it is widely used as a material for various parts of automobiles, electrical and electronic equipment, industrial materials, daily goods, household goods, and the like.

BACKGROUND ART In recent years, there has been a demand for weight reduction of automobiles in order to improve fuel efficiency of automobiles. Therefore, there is a demand for materials having mechanical properties such as low specific gravity and excellent strength and rigidity.

On the other hand, as a technique for further improving the sliding properties of polyamide resin, a composition is generally known in which solid lubricants such as fluororesin, graphite and molybdenum disulfide are blended and kneaded. In recent years, the use of resin for metal parts has been accelerating in the automotive, electric and electronic fields. There is a demand for molding materials with excellent properties and mechanical properties such as toughness and impact resistance.

Patent Document 1 proposes a composition in which a polyamide resin is mixed with a siloxane compound and a fluorine-based resin and melt-kneaded to improve sliding properties.

JP 2012-102189 A

In the technique described in Patent Document 1 and the like, slidability is improved by blending a siloxane compound or a fluororesin with a polyamide resin. However, the limit PV value, which is calculated by load pressure x speed, has not been improved. Moreover, since it is necessary to reduce wear and cracks in sliding members used in the automobile field, etc., improvement of impact resistance is also a subject.

The present invention has been made in view of the above circumstances, and provides a polyamide composition that provides a molded article with improved limit PV value and impact resistance, and a molded article and sliding member using the polyamide composition. To provide a method for improving the limit PV value and impact resistance of

That is, the present invention includes the following aspects.
(1) a polyamide;
an olefinic elastomer; and
an ethylene-styrene graft copolymer;
A polyamide composition comprising:
(2) The polyamide composition according to (1), wherein the polyamide contains at least one polyamide selected from the group consisting of polyamide 46 and polyamide 66.
(3) The polyamide composition according to (1) or (2), wherein the polyamide composition contains 5.00 parts by mass or more of the olefin elastomer with respect to 100.00 parts by mass of the polyamide.
(4) Any one of (1) to (3), wherein the polyamide composition contains 5.00 parts by mass or more of the ethylene-styrene graft copolymer with respect to 100.00 parts by mass of the polyamide. Polyamide composition according to.
(5) Molded from the polyamide composition according to any one of (1) to (4),
A molded body having a Rockwell hardness of more than 50 and less than 80 as measured on the M scale in accordance with ISO 2039-2:1987.
(6) The molded article according to (5), which has a surface free energy of 40 mJ/m ² or less as determined by the theoretical formula of Owens and Wendt.
(7) The molded article according to (5) or (6), which is a sliding member.
(8) A method for improving the limit PV value and impact resistance of a sliding member, comprising:
Obtaining a sliding member by molding a polyamide composition containing a polyamide, an olefin elastomer, and an ethylene-styrene graft copolymer,
A method according to ISO 2039-2, wherein the sliding member has a Rockwell hardness of more than 50 and less than 80 as measured on the M scale.

According to the polyamide composition of the aspect described above, it is possible to provide a polyamide composition from which a molded article having improved limit PV value and impact resistance can be obtained. The molded article of the above aspect is obtained by molding the polyamide composition, and has improved limit PV value and impact resistance. According to the method of the above aspect, the limit PV value and impact resistance of the sliding member can be improved.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "this embodiment") for implementing this invention is demonstrated in detail.
The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

As used herein, the term "polyamide" means a polymer having an amide (--NHCO--) bond in its main chain.

<<Polyamide composition>>
The polyamide composition of the present embodiment contains (A) a polyamide, (B) an olefinic elastomer, and (C) an ethylene-styrene graft copolymer. Hereinafter, these components may be abbreviated as component (A), component (B), and component (C), respectively.

With the polyamide composition of the present embodiment having the above structure, it is possible to obtain a molded article having improved limit PV value and impact resistance as compared with conventional ones.

The term "limit PV value" as used herein is a value calculated by multiplying the load pressure by the speed, and represents the limit value at which the sliding surface of the material wears or melts due to frictional heat generation. Therefore, by improving the critical PV value of the molded article, it is possible to obtain a molded article that is excellent in wear resistance and friction resistance even against high-load or high-speed sliding.

Moreover, the impact resistance can be evaluated by a Charpy impact value, as shown in Examples described later. The "Charpy impact value" is a value obtained by dividing the impact energy required to break a test piece by the cross-sectional area of the test piece as a result of the Charpy impact test. The Charpy impact value is used to express toughness. Therefore, by improving the Charpy impact value of the molded body, a molded body having excellent toughness (resistance to brittle fracture), that is, a molded body that is difficult to break can be obtained.

Next, each component constituting the polyamide composition of the present embodiment will be described in detail below.

<Constituent>
[(A) Polyamide]
(A) The polyamide is not limited to the following, but for example, (Aa) a polyamide obtained by ring-opening polymerization of a lactam, (Ab) a polyamide obtained by self-condensation of ω-aminocarboxylic acid, (A -c) polyamides obtained by condensing diamines and dicarboxylic acids, copolymers thereof, and the like. (A) Polyamides may be used singly or in combination of two or more.

(Aa) Examples of the lactam used in producing the polyamide include, but are not limited to, pyrrolidone, caprolactam, undecalactam, dodecalactam, and the like.
(Ab) The ω-aminocarboxylic acid used in producing the polyamide is not limited to the following, but includes, for example, ω-amino fatty acids, which are ring-opening compounds of the above lactams with water.
As the lactam or the ω-aminocarboxylic acid, two or more monomers may be used in combination and condensed.

(Ac) Diamines (monomers) used in the production of polyamides are not limited to the following, but examples include linear aliphatic diamines, branched aliphatic diamines, alicyclic diamines, aromatic group diamines and the like.
Linear aliphatic diamines include, but are not limited to, hexamethylenediamine, pentamethylenediamine, and the like.
Examples of branched aliphatic diamines include, but are not limited to, 2-methylpentanediamine, 2-ethylhexamethylenediamine, and the like.
Examples of the alicyclic diamine include, but are not limited to, cyclohexanediamine, cyclopentanediamine, cyclooctanediamine, and the like.
Examples of aromatic diamines include, but are not limited to, p-phenylenediamine, m-phenylenediamine, and the like.
(Ac) The dicarboxylic acid (monomer) used for producing the polyamide is not limited to the following, and examples thereof include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids.
Examples of aliphatic dicarboxylic acids include, but are not limited to, adipic acid, pimelic acid, sebacic acid, and the like.
Examples of the alicyclic dicarboxylic acid include, but are not limited to, cyclohexanedicarboxylic acid.
Examples of aromatic dicarboxylic acids include, but are not limited to, phthalic acid, isophthalic acid, and the like.
The above diamines and dicarboxylic acids as monomers may be condensed singly or in combination of two or more.

In addition, (A) polyamide may further contain units derived from polyvalent carboxylic acids having a valence of 3 or more, such as trimellitic acid, trimesic acid, and pyromellitic acid, if necessary. The trivalent or higher polyvalent carboxylic acid may be used alone or in combination of two or more.

(A) Specific examples of polyamides include polyamide 4 (polyα-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (polytetra methylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonanemethylene terephthalamide), and copolymerized polyamides containing these as constituents.
Among them, (A) polyamide is preferably polyamide 46 (PA46) or polyamide 66 (PA66). PA66 is excellent in heat resistance, moldability and toughness, and is therefore a suitable material for automobile parts.

(Terminal blocking agent)
(A) The terminal of the polyamide may be terminal-blocked with a known terminal-blocking agent.
Such a terminal blocker is also used as a molecular weight modifier when producing a polyamide from the dicarboxylic acid, the diamine, and, if necessary, at least one of the lactam and the aminocarboxylic acid. can be added.

Examples of terminal blocking agents include, but are not limited to, monocarboxylic acids, monoamines, acid anhydrides, monoisocyanates, monoacid halides, monoesters, and monoalcohols. Examples of acid anhydrides include, but are not limited to, phthalic anhydride. These terminal blocking agents may be used alone or in combination of two or more.
Among them, a monocarboxylic acid or a monoamine is preferable as the terminal blocking agent. By blocking the ends of the polyamide with a terminal blocking agent, the polyamide composition tends to be more excellent in thermal stability.

As the monocarboxylic acid that can be used as the terminal blocker, any one having reactivity with the amino group that can be present at the terminal of the polyamide can be used. Specific examples of monocarboxylic acids include, but are not limited to, aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and aromatic monocarboxylic acids.
Examples of aliphatic monocarboxylic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid and the like.
Examples of the alicyclic monocarboxylic acid include, but are not limited to, cyclohexanecarboxylic acid.
Examples of aromatic monocarboxylic acids include, but are not limited to, benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid.
These monocarboxylic acids may be used alone or in combination of two or more.

As the monoamine that can be used as the terminal blocker, any one having reactivity with the carboxy group that can be present at the terminal of the polyamide may be used. Specific examples of monoamines include, but are not limited to, aliphatic monoamines, alicyclic monoamines, and aromatic monoamines.
Examples of aliphatic amines include, but are not limited to, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine. etc.
Examples of the alicyclic amine include, but are not limited to, cyclohexylamine, dicyclohexylamine, and the like.
Examples of aromatic amines include, but are not limited to, aniline, toluidine, diphenylamine, naphthylamine, and the like.
These monoamines may be used individually by 1 type, and may be used in combination of 2 or more types.

Polyamide compositions containing polyamides end-capped with end-capping agents tend to be superior in heat resistance, fluidity, toughness, low water absorption and rigidity.

((A) polyamide content)
The content of (A) polyamide in the polyamide composition can be, for example, 50.0% by mass or more and 99.0% by mass or less, relative to the total mass of the polyamide composition, for example 60.0% by mass or more It can be 95.0% by mass or less, for example, 70.0% by mass or more and 90.0% by mass or less.

((A) Method for producing polyamide)
(A) When producing the polyamide, it is preferable that the amount of the dicarboxylic acid and the amount of the diamine added are approximately the same molar amount. Considering the amount of diamine that escapes to the outside of the reaction system during the polymerization reaction, the molar ratio of the total diamine to the total molar amount of the dicarboxylic acid is preferably 0.9 or more and 1.2 or less. , is preferably 0.95 or more and 1.1 or less, more preferably 0.98 or more and 1.05 or less.
The method for producing a polyamide is not limited to the following, but for example, a dicarboxylic acid that constitutes a dicarboxylic acid unit, a diamine that constitutes a diamine unit, and, if necessary, a lactam and an amino that constitute a lactam unit. It includes a step of polymerizing at least one of aminocarboxylic acids constituting carboxylic acid units to obtain a polymer.
Moreover, it is preferable that the method for producing a polyamide further includes a step of increasing the degree of polymerization of the polyamide.
In addition, a blocking step of blocking the ends of the obtained polymer with a terminal blocking agent may be included as necessary.

Specific methods for producing polyamides include, for example, various methods exemplified in 1) to 4) below.
1) A method of heating an aqueous solution of a dicarboxylic acid-diamine salt or a mixture of a dicarboxylic acid and a diamine, or a suspension of these water, and polymerizing while maintaining the molten state (hereinafter referred to as "thermal melt polymerization method" sometimes referred to as).
2) A method of increasing the degree of polymerization of a polyamide obtained by a hot melt polymerization method while maintaining a solid state at a temperature below the melting point (hereinafter sometimes referred to as "hot melt polymerization/solid phase polymerization method").
3) A method of polymerizing a dicarboxylic acid-diamine salt or a mixture of a dicarboxylic acid and a diamine while maintaining the solid state (hereinafter sometimes referred to as "solid phase polymerization method").
4) A method of polymerizing using a dicarboxylic acid halide component and a diamine component equivalent to the dicarboxylic acid (hereinafter sometimes referred to as "solution method").
Among them, as a specific method for producing a polyamide, a production method including a hot melt polymerization method is preferable. Moreover, when producing a polyamide by a hot melt polymerization method, it is preferable to maintain a molten state until the polymerization is completed. As a method of maintaining the molten state, for example, a method of producing under polymerization conditions suitable for the composition of the polyamide can be mentioned. Polymerization conditions include, for example, the conditions shown below. First, the polymerization pressure in the hot melt polymerization method is controlled to 14 kg/cm ² or more and 25 kg/cm ² or less (gauge pressure), and heating is continued. Next, the pressure in the tank is lowered to atmospheric pressure (gauge pressure is 0 kg/cm ² ) over 30 minutes or more to obtain a polyamide having a desired composition.

In the method for producing polyamide, the form of polymerization is not particularly limited, and may be a batch system or a continuous system.
The polymerization apparatus used for the production of polyamide is not particularly limited, and known apparatuses can be used. For example, an autoclave reactor, a tumbler reactor, an extruder reactor such as a kneader, etc. mentioned.

As a method for producing a polyamide, a method for producing a polyamide by a batch-type hot-melt polymerization method will be specifically described below, but the method for producing a polyamide is not limited to this.
First, an aqueous solution containing about 40% by mass or more and 60% by mass or less of polyamide raw material components (dicarboxylic acid, diamine, and, if necessary, at least one of lactam and aminocarboxylic acid) C. or less and a pressure of about 0.035 MPa or more and 0.6 MPa or less (gauge pressure) to concentrate to about 65 mass % or more and 90 mass % or less to obtain a concentrated solution.
The resulting concentrated solution is then transferred to an autoclave and heating is continued until the pressure in the autoclave is about 1.2 MPa to 2.2 MPa (gauge pressure).
After that, in the autoclave, the pressure is maintained at about 1.2 MPa or more and 2.2 MPa or less (gauge pressure) while removing at least one of water and gas components, and when the temperature reaches about 220 ° C. or more and 260 ° C. or less, Reduce the pressure to atmospheric pressure (gauge pressure is 0 MPa).
By reducing the pressure in the autoclave to atmospheric pressure and then reducing the pressure as necessary, water produced as a by-product can be effectively removed.
The autoclave is then pressurized with an inert gas such as nitrogen to extrude the polyamide melt from the autoclave as a strand. The extruded strand is cooled and cut to obtain polyamide pellets.

(Polymer end of polyamide)
(A) Polyamide polymer ends are not particularly limited, but can be classified and defined as follows.
2) the carboxy terminus; 3) the capped terminus; 4) the other terminus.
1) Amino terminus is a polymer terminus having an amino group ( _--NH2 group) and is derived from the starting diamine unit.
2) The carboxy terminus is a polymer terminus having a carboxy group (--COOH group), which is derived from the raw material dicarboxylic acid.
3) Terminals formed by a capping agent are terminals formed when a capping agent is added during polymerization. The terminal blocking agent mentioned above is mentioned as a blocking agent.
4) Other terminals are polymer terminals not classified in 1) to 3) above. Specific examples of other terminals include terminals generated by deammonification of amino terminals, terminals generated by decarboxylation of carboxy terminals, and the like.

[(B) Olefin-based elastomer]
By including (B) an olefin elastomer, the polyamide composition can reduce the surface free energy and further improve the impact resistance. As a result, the molded article has excellent abrasion resistance, wear resistance, and limit PV value.

(B) The olefin-based elastomer is not limited to the following. Enterpolymers and the like can be mentioned. Further, these olefinic elastomers may be modified with an acid. Specific examples of acid-modified olefinic elastomers include maleic anhydride-modified olefinic elastomers, maleic acid-modified olefinic elastomers, and itaconic anhydride-modified olefinic elastomers. system elastomers, itaconic acid-modified olefin-based elastomers, fumaric acid-modified olefin-based elastomers, methacrylic acid-modified olefin-based elastomers, acrylic acid-modified olefin-based elastomers, and the like. These olefinic elastomers may be used alone or in combination of two or more.

(Content of (B) olefin elastomer)
The content of the (B) olefin elastomer in the polyamide composition can be 4.00 parts by mass or more, and is 5.00 parts by mass or more with respect to 100.00 parts by mass of the (A) polyamide. is preferably 7.00 parts by mass or more, more preferably 9.00 parts by mass or more. When the content of the olefin elastomer (B) is at least the above lower limit, the surface free energy can be further reduced, and the impact resistance can be further improved. As a result, the molded article has better friction resistance, wear resistance, and limit PV value. On the other hand, the content of the (B) olefin elastomer in the polyamide composition is preferably 20.00 parts by mass or less, and 15.00 parts by mass or less, relative to 100.00 parts by mass of the (A) polyamide. is more preferable. (B) When the content of the olefinic elastomer is equal to or less than the above upper limit, the mechanical properties of the molded article are further improved.

[(C) Ethylene-styrene graft copolymer]
Polyamide composition, (C) ethylene - by containing a styrene graft copolymer, it is possible to improve the impact resistance (Charpy impact value) of the molded body, also excellent abrasion resistance of the molded body Become.
(C) The ethylene-styrene graft copolymer is a graft copolymer in which side chains containing polystyrene are grafted to a main chain containing polyethylene, and is an olefinic polymer (preferably polyethylene) containing polyethylene in the main chain. Moreover, it is preferably a graft copolymer obtained by graft-copolymerizing a vinyl polymer such as polystyrene as a side chain.

(C) The method for preparing the ethylene-styrene graft copolymer is not particularly limited, but it can be easily prepared by a known radical reaction. For example, a method of adding a radical catalyst to a monomer constituting an olefin-based polymer component including polyethylene and a monomer constituting a vinyl-based polymer and kneading them for grafting, or an olefin-based polymer component or a vinyl-based polymer. A graft copolymer is prepared by adding a radical catalyst such as a peroxide to one of the components to generate free radicals, which are then melt-kneaded with the polymer of the other component for grafting.

(C) The ratio of (c1) olefin polymer and (c2) vinyl polymer constituting ethylene-styrene graft copolymer is preferably c1:c2 = 90:10 to 10:90 (mass ratio), More preferably, c1:c2=80:20 to 20:80.

((C) Ethylene-styrene graft copolymer content)
The content of (C) ethylene-styrene graft copolymer in the polyamide composition is preferably 5.00 parts by mass or more with respect to 100.00 parts by mass of (A) polyamide, and 5.30 parts by mass It is more preferably 5.50 parts by mass or more, and particularly preferably 5.70 parts by mass or more.
(C) ethylene in the polyamide composition - the content of the styrene graft copolymer is at least the above lower limit, it is possible to further reduce the coefficient of friction of the molded body, also wear resistance of the molded body is improved. become better. On the other hand, the content of (C) ethylene-styrene graft copolymer in the polyamide composition is preferably 15.00 parts by mass or less, more preferably 12.00 parts by mass or less, and 10.00 It is more preferably not more than parts by mass. When the content of the ethylene-styrene graft copolymer (C) is equal to or less than the above upper limit, the mechanical properties of the molded article are further improved.

[(D) copper compound]
The polyamide composition can further contain (D) a copper compound in addition to the above components (A) to (C).

(C) Copper compounds include copper halide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate; ethylenediamine, ethylenediamine A copper complex salt coordinated with a chelating agent such as tetraacetic acid can be mentioned. These copper compounds may be used alone or in combination of two or more. Among these, copper iodide, cuprous bromide, cupric bromide, cuprous chloride, or copper acetate is preferable, and copper iodide is more preferable. From the viewpoint of sliding properties, these copper compounds are preferably used in the form of a masterbatch with (E) a metal halide selected from the group consisting of alkali metals and alkaline earth metals, which will be described later.

The content of the copper compound in the polyamide composition is preferably 0.0001 parts by mass or more and 1.00 parts by mass or less, and 0.005 parts by mass or more and 0.20 mass parts with respect to 100.00 parts by mass of the polyamide (A) Part or less is more preferable, and 0.01 to 0.10 part by mass is even more preferable.

[(E) a metal halide selected from the group consisting of alkali metals and alkaline earth metals]
In addition to the components (A) to (C), the polyamide composition contains (E) a metal halide selected from the group consisting of alkali metals and alkaline earth metals (hereinafter referred to as "metal halide"). may be omitted) can be further included.

Examples of metal halides include potassium iodide, sodium iodide, potassium bromide, potassium chloride, sodium chloride and the like. Among these, potassium iodide is preferred. These metal halides may be used alone or in combination of two or more.

The content of the metal halide in the polyamide composition is preferably 0.0001 parts by mass or more and 3.00 parts by mass or less, and 0.005 parts by mass or more and 1.00 parts by mass with respect to 100.00 parts by mass of the polyamide (A) It is more preferably not more than 0.02 part by mass and even more preferably 0.50 part by mass or less.

[(F) Colorant]
The polyamide composition can further contain (F) a colorant in addition to the above components (A) to (C).

Colorants include, but are not limited to, dyes such as nigrosine, pigments such as titanium oxide and carbon black; aluminum, colored aluminum, nickel, tin, copper, gold, silver, platinum, iron oxide, stainless steel, and titanium. metallic particles such as mica pearl pigments and colored graphite. These colorants may be used alone or in combination of two or more.

The content of the coloring agent in the polyamide composition is preferably 0.0001 parts by mass or more and 1.00 parts by mass or less, and 0.001 parts by mass or more and 0.50 parts by mass with respect to 100.00 parts by mass of the polyamide (A) Part or less is more preferable, and 0.005 to 0.10 part by mass is even more preferable.

[(G) Other components]
In addition to the above components (A) to (C), the polyamide composition further contains (G) other components, if necessary, within a range that does not impair the effects of the polyamide composition of the present embodiment. can be done.

(G) Other components include (G1) lubricants, (G2) heat stabilizers, (G3) fillers, (G4) other resins, and the like.

((G1) lubricant)
(G1) Lubricants include, but are not limited to, higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, higher fatty acid amides, and the like.

Examples of higher fatty acids include linear or branched, saturated or unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms.
Examples of linear or branched saturated or unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include lauric acid, palmitic acid, stearic acid, behenic acid and montanic acid.
Examples of branched-chain saturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include isopalmitic acid and isostearic acid.
Examples of linear unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include oleic acid and erucic acid.
Examples of branched unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include isoleic acid.
One of these higher fatty acids may be used alone, or two or more of them may be used in combination.
Among them, stearic acid or montanic acid is preferable as the higher fatty acid.

A higher fatty acid metal salt is a metal salt of a higher fatty acid.
Examples of the metal elements of the metal salt include Group 1 elements, Group 2 elements and Group 3 elements of the periodic table of elements, zinc, aluminum and the like.
Group 1 elements of the periodic table of elements include, for example, sodium and potassium.
Group 2 elements of the periodic table of elements include, for example, calcium and magnesium.
Group 3 elements of the periodic table of elements include, for example, scandium and yttrium.
Among them, the metal element is preferably an element of Groups 1 and 2 of the periodic table or aluminum, and more preferably sodium, potassium, calcium, magnesium or aluminum.

Specific examples of higher fatty acid metal salts include calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium montanate, sodium montanate, and calcium palmitate.
One of these higher fatty acid metal salts may be used alone, or two or more of them may be used in combination.
Among them, as the higher fatty acid metal salt, a metal salt of montanic acid or a metal salt of stearic acid is preferable.

Higher fatty acid esters are esters of higher fatty acids and alcohols.
As the higher fatty acid ester, an ester of an aliphatic carboxylic acid having 8 to 40 carbon atoms and an aliphatic alcohol having 8 to 40 carbon atoms is preferable.
Examples of aliphatic alcohols having 8 to 40 carbon atoms include stearyl alcohol, behenyl alcohol, and lauryl alcohol.
Specific examples of higher fatty acid esters include stearyl stearate and behenyl behenate.
These higher fatty acid esters may be used singly or in combination of two or more.

A higher fatty acid amide is an amide compound of a higher fatty acid.
Examples of higher fatty acid amides include stearic acid amide, oleic acid amide, erucic acid amide, ethylenebisstearylamide, ethylenebisoleylamide, N-stearyl stearic acid amide, N-stearyl erucic acid amide and the like.
These higher fatty acid amides may be used singly or in combination of two or more.

The content of the lubricant in the polyamide composition is preferably 0.001 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the polyamide (A) in the polyamide composition, and 0.03 parts by mass or more and 0.5 Part by mass or less is more preferable.
When the content of the lubricant is within the above range, it is possible to obtain a polyamide composition which is more excellent in releasability and plasticization time stability, and which is also more excellent in toughness. In addition, it is possible to more effectively prevent an extreme reduction in the molecular weight of the polyamide due to scission of the molecular chain.

((G2) heat stabilizer)
(G2) The heat stabilizer is not limited to the following, but includes, for example, phenol-based heat stabilizers, phosphorus-based heat stabilizers, amine-based heat stabilizers, and the like.

Phenolic heat stabilizers include, but are not limited to, hindered phenol compounds. Hindered phenol compounds have the property of imparting excellent heat resistance and light resistance to resins such as polyamides and fibers.

Examples of the hindered phenol compound include, but are not limited to, N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylprop onamide), pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl- 4-hydroxy-hydrocinnamamide), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3 -tert-butyl-4-hydroxy-5-methylphenyl)propynyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, 3,5-di-tert -butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5 -tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid and the like.
These hindered phenol compounds may be used alone or in combination of two or more.
In particular, from the viewpoint of improving heat aging resistance, the hindered phenol compound includes N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide )] is preferred.

When using a phenolic heat stabilizer, the content of the phenolic heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the phenolic heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved and the amount of gas generated can be further reduced.

Examples of phosphorus-based heat stabilizers include, but are not limited to, pentaerythritol-type phosphite compounds, trioctylphosphite, trilaurylphosphite, tridecylphosphite, octyldiphenylphosphite, trisisodecyl Phosphite, phenyldiisodecylphosphite, phenyldi(tridecyl)phosphite, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyl(tridecyl)phosphite, triphenylphosphite, tris(nonylphenyl)phosphite, tris(2 ,4-di-tert-butylphenyl)phosphite, tris(2,4-di-tert-butyl-5-methylphenyl)phosphite, tris(butoxyethyl)phosphite, 4,4'-butylidene-bis( 3-methyl-6-tert-butylphenyl-tetra-tridecyl)diphosphite, tetra(C12-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite, 4,4'-isopropylidenebis(2-tert -butylphenyl)-di(nonylphenyl)phosphite, tris(biphenyl)phosphite, tetra(tridecyl)-1,1,3-tris(2-methyl-5-tert-butyl-4-hydroxyphenyl)butanedi Phosphites, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenyl) diphosphite, tetra(C1-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite, tris (mono, dimixed nonylphenyl) phosphite, 4,4′-isopropylidenebis(2-tert-butylphenyl)-di(nonylphenyl)phosphite, 9,10-di-hydro-9-oxa-9- Oxa-10-phosphaphenanthrene-10-oxide, tris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite, hydrogenated-4,4′-isopropylidene diphenyl polyphosphite, bis (Octylphenyl)-bis(4,4′-butylidenebis(3-methyl-6-tert-butylphenyl))-1,6-hexanol diphosphite, hexatridecyl-1,1,3-tris(2- methyl-4-hydroxy-5-tert-butylphenyl)diphosphite, tris(4,4'-isopropylidenebis(2-tert-butylphenyl) )) phosphite, tris(1,3-stearoyloxyisopropyl)phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite, 2,2-methylenebis(3-methyl- 4,6-di-tert-butylphenyl)2-ethylhexylphosphite, tetrakis(2,4-di-tert-butyl-5-methylphenyl)-4,4'-biphenylenediphosphite, tetrakis(2,4 -di-tert-butylphenyl)-4,4'-biphenylene diphosphite and the like.
These phosphorus-based heat stabilizers may be used alone or in combination of two or more.
Among them, as the phosphorus-based heat stabilizer, pentaerythritol type phosphite compound and tris(2,4-di-tert-butylphenyl ) one or more selected from the group consisting of phosphites.

Examples of pentaerythritol-type phosphite compounds include, but are not limited to, 2,6-di-tert-butyl-4-methylphenyl-phenyl-pentaerythritol diphosphite, 2,6-di- tert-butyl-4-methylphenyl-methyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-2-ethylhexyl-pentaerythritol diphosphite, 2,6-di-tert- Butyl-4-methylphenyl-isodecyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-lauryl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4- Methylphenyl-isotridecyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-stearyl pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl cyclohexyl -pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-benzyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl ethyl cellosolve-pentaerythritol Diphosphite, 2,6-di-tert-butyl-4-methylphenyl-butylcarbitol-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-octylphenyl-pentaerythritol diphosphite phosphites, 2,6-di-tert-butyl-4-methylphenyl-nonylphenyl pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, Bis(2,6-di-tert-butyl-4-ethylphenyl) pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-2,6-di-tert-butylphenyl-penta Erythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl-2,4-di-tert-butylphenyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methyl Phenyl-2,4-di-tert-octylphenyl-pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl -2-cyclohexylphenyl-pentaerythritol diphosphite, 2,6-di-tert-amyl-4-methylphenyl-phenyl pentaerythritol diphosphite, bis(2,6-di-tert-amyl-4 -methylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-octyl-4-methylphenyl)pentaerythritol diphosphite and the like.
These pentaerythritol-type phosphite compounds may be used alone or in combination of two or more.

Among them, as the pentaerythritol-type phosphite compound, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2 ,6-di-tert-butyl-4-ethylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-amyl-4-methylphenyl)pentaerythritol diphosphite, and bis(2,6 -di-tert-octyl-4-methylphenyl)pentaerythritol diphosphite, preferably one or more selected from the group consisting of bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite Fight is more preferred.

When using a phosphorus-based heat stabilizer, the content of the phosphorus-based heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the phosphorus-based heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved, and the amount of gas generated can be further reduced.

Examples of amine heat stabilizers include, but are not limited to, 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetra methylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(phenylacetoxy)-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6, 6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6, 6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-2,2 ,6,6-tetramethylpiperidine, 4-(cyclohexylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(phenylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl)-carbonate, bis(2,2,6,6-tetramethyl-4-piperidyl)-oxalate, bis(2,2,6,6-tetra methyl-4-piperidyl)-malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)-sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)-adipate, bis (2,2,6,6-tetramethyl-4-piperidyl)-terephthalate, 1,2-bis(2,2,6,6-tetramethyl-4-piperidyloxy)-ethane, α,α'-bis (2,2,6,6-tetramethyl-4-piperidyloxy)-p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyl tolylene-2,4-dicarbamate, bis ( 2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene-1,6-dicarbamate, tris(2,2,6,6-tetramethyl-4-piperidyl)-benzene-1,3, 5-tricarboxylate, tris(2,2,6,6-tetramethyl-4-piperidyl)-benzene-1,3,4-tricarboxylate, 1-[2-{3-(3,5-di -tert-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-tert-butyl-4- Hydroxyphenyl)propionyloxy]2,2,6,6-tetramethylpiperidine, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β,β , β', β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro(5,5)undecane]diethanol.
These amine heat stabilizers may be used alone or in combination of two or more.

When using an amine-based heat stabilizer, the content of the amine-based heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the amine-based heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved, and the amount of gas generated can be further reduced.

((G3) filler)
The polyamide composition can be used as a sliding member with improved Charpy impact value and limit PV value in addition to excellent slidability even without the (G3) filler. It may further contain:

(G3) Fillers include, but are not limited to, carbon fibers, glass fibers, calcium silicate fibers, potassium titanate fibers, aluminum borate fibers, wollastonite, carbon nanotubes, and the like. be done. Among these, carbon fiber or glass fiber is preferable, glass fiber is preferable from the viewpoint of increasing the strength of the polyamide composition, and carbon fiber is preferable from the viewpoint of improving slidability.
As carbon fibers, for example, both polyacrylonitrile (PAN)-based carbon fibers and pitch-based carbon fibers can be used. From the viewpoint of mechanical properties, it is preferable to use PAN-based carbon fiber.
The above fillers may be used alone or in combination of two or more.

From the viewpoint of improving the sliding properties, the content of the filler in the polyamide composition is preferably 1 part by mass or more and 30 parts by mass or less, and 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polyamide (A). is more preferable, and 5 parts by mass or more and 10 parts by mass or less is even more preferable.

From the viewpoint of productivity, carbon fibers are preferably added in the form of short fibers of about 3 mm to 10 mm by melt-kneading with an extruder. At that time, from the viewpoint of preventing the carbon fibers from breaking, it is preferable to add the carbon fibers from a side feeder.

Carbon fibers are preferably coated with a urethane-based sizing agent, a maleic anhydride-based sizing agent, an acrylic-based sizing agent, or a polyamide-based sizing agent from the viewpoint of affinity with polyamide resins.
From the viewpoint of physical properties and slidability, the carbon fiber preferably has a diameter of 5 μm or more and 10 μm or less.

((G4) other resins)
(G4) Other resins include, but are not limited to, thermoplastic resins and rubber components, which will be described later.

Examples of thermoplastic resins include polystyrene resins such as atactic polystyrene, isotactic polystyrene, syndiotactic polystyrene, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin; Acrylic resins such as acrylic acid esters and polymethyl methacrylate; halogen-containing vinyl compound resins such as polyvinyl chloride and polyvinylidene chloride;
These thermoplastic resins may be used alone or in combination of two or more.

Examples of rubber components include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiocol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene-butadiene block copolymer (SBR), Hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR ), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene random copolymer , hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, styrene-ethylene-butylene random copolymer, ethylene-propylene copolymer (EPR), ethylene-(1-butene) copolymer ethylene-(1-hexene) copolymer, ethylene-(1-octene) copolymer, ethylene-propylene-diene copolymer (EPDM), butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene-core shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core-shell rubber (MAS), octyl acrylate-butadiene-styrene-core-shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene core-shell rubber ( AABS), butadiene-styrene-core-shell rubber (SBR), and siloxane-containing core-shell rubbers such as methyl methacrylate-butyl acrylate siloxane.
These rubber components may be used alone or in combination of two or more.

<Method for producing polyamide composition>
The method for producing the polyamide composition is not particularly limited as long as it is a production method including a step of melt-kneading the raw material components including the component (A) to the component (C).
In the melt-kneading step, for example, when the raw material components are melt-kneaded by an extruder, the set temperature of the extruder is preferably the melting point (Tm2) of the polyamide (A) + 30°C or less.

(A) Examples of the method of melt-kneading raw material components containing polyamide include the following methods (1) and (2).
(1) A method of mixing (A) polyamide and other raw materials using a tumbler, a Henschel mixer, etc., and supplying the mixture to a melt-kneader for kneading.
(2) A method of blending other raw materials from a side feeder into (A) polyamide which has been melted by a single-screw or twin-screw extruder.

As for the method of supplying the components constituting the polyamide composition to the melt kneader, all the components may be supplied to the same supply port at once, or the components may be supplied from different supply ports.

The melt-kneading temperature is preferably about 250° C. or higher and 350° C. or lower in terms of resin temperature.
The melt-kneading time is preferably about 0.25 minutes or more and 5 minutes or less.
The apparatus for melt-kneading is not particularly limited, and known apparatuses such as single-screw or twin-screw extruders, Banbury mixers, mixing rolls, and other melt-kneaders can be used.

The blending amount of each component when producing the polyamide composition is the same as the content of each component in the polyamide composition described above.

≪Molded body≫
The molded article of this embodiment is obtained by molding the polyamide composition described above.

By having the above structure, the molded article of the present embodiment has improved limit PV value and impact resistance as compared with conventional ones. Therefore, the molded article of this embodiment is preferably used as a sliding member. That is, in one embodiment, the present invention provides a method for improving the critical PV value and impact resistance of a sliding member.

In the molded article of the present embodiment, the Rockwell hardness measured on the M scale is more than 50 and less than 80, preferably 51 or more and 79 or less, more preferably 55 or more and 78 or less, and 60 or more and 77 or less. is more preferable.
When the Rockwell hardness of the molded article is within the above numerical range, the coefficient of friction can be reduced, and a molded article having excellent wear resistance and friction resistance and a further improved limit PV value can be obtained.

The Rockwell hardness of the molded body can be measured on the M scale according to ISO 2039-2:1987 using a hardness tester (Akashi ATK-F3000, manufactured by Akashi Seisakusho Co., Ltd.).

The surface free energy of the molded article of the present embodiment is preferably 40 mJ/m ² or less. The term "Surface Free Energy (SFE)" as used herein means surface tension acting on the surface of a solid due to intermolecular forces. The unit of surface free energy is expressed in mN/m or mJ/ ^m2 . The higher the energy value, the more likely the solid will be wetted by another solid or liquid. Therefore, when the surface free energy of the molded body of the present embodiment is equal to or less than the above upper limit value, the interaction with another member is further reduced, resulting in superior wear resistance and friction resistance.
On the other hand, the lower limit of the surface free energy of the compact is not particularly limited, but can be set to 35 mJ/m ² , for example.

The surface free energy of the molded article is obtained by measuring the contact angle between pure water and diiodomethane and the molded article using, for example, a contact angle meter (model: B100W, manufactured by Asumi Giken Co., Ltd.), and using the obtained contact angle. can be obtained from the theoretical formula of Owens and Wendt. Specifically, it is calculated using the following formula.

In the above formula A, γSV is the surface free energy of the compact, and the components of the surface free energy of the compact are the dispersion component (γSV ^d ) and the component based on hydrogen bonding and dipole-dipole interaction (γSV ^h ).

In order to obtain the two unknown components (γSV ^d and γSV ^h ) in the surface free energy (γSV) of the compact, two types of liquids (pure water and diiodomethane) with known surface free energies were used as described above. , using a contact angle meter, measure the contact angle between pure water and diiodomethane and the compact. The obtained pure water contact angle θ ₁ and diiodomethane contact angle θ ₂ , the known pure water dispersion component (γLV1 ^d ) and the component based on hydrogen bonding and dipole-dipole interaction (γLV1 ^h ), and Substituting the known dispersion component (γLV2 ^d ) of diiodomethane and the component (γLV2 ^h ) based on hydrogen bonding and dipole-dipole interaction into the above formulas B and C, respectively, the surface free energy of the compact ( γSV) with two unknown components (γSV ^d and γSV ^h ) is derived and solved to obtain the surface free energy (γSV).

Next, the polyamide composition, which is the raw material of the molded article of the present embodiment, will be described below.

<Method for manufacturing molded body>
Examples of the method for producing a molded article include a production method including a step of melting pellets of the polyamide composition and molding using a mold having one or more flow gates.

The blending amount of each component when producing the molded article of the present embodiment is the same as the content of each component in the polyamide composition described above.

Also, the molded article of the present embodiment is obtained by molding the polyamide composition using a known injection molding method.
Examples of known molding methods include, but are not limited to, generally known plastic injection molding methods such as injection molding and gas-assisted injection molding.

The set temperature of the molding machine when molding the molded article of the present embodiment is preferably set in the range of 5 ° C. higher than the melting point of the polyamide to be used to 310 ° C., and 10 ° C. higher than the melting point of the polyamide to be used. More preferably, the temperature ranges from 15°C above the melting point of the polyamide used to 295°C. By setting the temperature of the molding machine to the above upper limit or less, it is possible to suppress the melting and aggregation of the component (B) and the component (C) during melting and injection of the polyamide composition, and in the molded product can sufficiently disperse the component (B) and the component (C).

<Application>
The molded article of the present embodiment has excellent sliding properties and improved impact resistance and limit PV value. Therefore, the molded article of this embodiment can be suitably used as a sliding member that requires high performance in a wide range of fields such as electrical and electronic equipment, office equipment, automobiles, and industrial equipment. Specific examples of sliding members used in these fields include bearings, gears, cams, rollers, accelerator pedal rotors, sliding plates, pulleys, levers, chain guides, and shoes.

EXAMPLES The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.
In the examples, 1 kg/cm ² means 0.098 MPa.

<raw materials>
Each raw material contained in the polyamide composition will be described below.

[(A) Polyamide]
A-1: Polyamide 66 (PA66) (manufactured by Asahi Kasei Corporation, trade name “Leona 1300 301”)

[(B) Olefin-based elastomer]
B-1: Ethylene-octane copolymer (manufactured by Dupont, trade name "Fusabond MN495D")
B-2: Ethylene-octane (EO)-based polyolefin elastomer (POE) (manufactured by Dow Chemical Company, trade name “Engage 8180”)

[(C) Ethylene-styrene graft copolymer]
C-1: Low-density polyethylene-polystyrene graft copolymer (manufactured by NOF Corporation, trade name “Modiper A1100”)

[(D) copper compound]
D-1: Copper iodide (CuI) (trade name “copper iodide (I)”, manufactured by Wako Pure Chemical Industries, Ltd.)

[(E) metal halide E-1: potassium iodide (KI) (trade name “potassium iodide”, manufactured by Wako Pure Chemical Industries, Ltd.)

[(F) Colorant]
F-1: carbon black (CB)

[(H) slidability improver]
H-1: Polytetrafluoroethylene (PTFE) (manufactured by Mitsui-DuPont Fluorochemicals, trade name “TLP10F-1”, number average primary particle size 0.2 μm, melting point 329 ° C., number average molecular weight 300000 (low molecular weight PTFE ))
H-2: Dimethyl silicone (manufactured by Dow Chemical Company, trade name “SH200”)

<Method for measuring physical properties of compact>
[Production of molding]
Using an injection molding machine (manufactured by Fanuc), the cooling time is set to 15 seconds, the screw rotation speed is 100 rpm, the mold temperature is set to 80 ° C., and the cylinder temperature is set to 270 ° C. or higher and 280 ° C. or lower. (length 180 mm, width 20 mm, thickness 2 mm or 4 mm) and molded body 2 (JIS K 7218 A type) were produced.

[Physical properties 1]
(Rockwell hardness)
For each compact 1, the Rockwell hardness was measured on the M scale in accordance with ISO 2039-2:1987 using a hardness tester (Akashi ATK-F3000, manufactured by Akashi Seisakusho Co., Ltd.).

[Physical properties 2]
(Surface free energy)
For each compact 1, a contact angle meter (model: B100W, manufactured by Asumi Giken Co., Ltd.) was used to measure the contact angle between pure water and diiodomethane and the compact. It was obtained by the theoretical formula of Specifically, it was calculated using the following formula.

In the above formula A, γSV is the surface free energy of the compact, and the components of the surface free energy of the compact are the dispersion component (γSV ^d ) and the component based on hydrogen bonding and dipole-dipole interaction (γSV ^h ).

In order to obtain the two unknown components (γSV ^d and γSV ^h ) in the surface free energy (γSV) of the compact, two types of liquids (pure water and diiodomethane) with known surface free energies were used as described above. , a contact angle meter (model: B100W, manufactured by Asumi Giken Co., Ltd.) was used to measure the contact angles between pure water and diiodomethane and the compact. The obtained pure water contact angle θ ₁ and diiodomethane contact angle θ ₂ , the known pure water dispersion component (γLV1 ^d ) and the component based on hydrogen bonding and dipole-dipole interaction (γLV1 ^h ), and Substituting the known diiodomethane dispersion component (γLV2 ^d ) and the component (γLV2 ^h ) based on hydrogen bonding and dipole-dipole interaction into the above formulas B and C, respectively, the surface free energy of the compact ( A linear equation with two unknown components (γSV ^d and γSV ^h ) in γSV) was derived and solved to obtain the surface free energy (γSV).

<Evaluation method>
[Evaluation 1]
(Charpy impact value)
Each compact 1 was processed to 80×10×4 mm, and the notched Charpy impact value (kJ/m ² ) was measured according to ISO179.

[Evaluation 2]
(limit PV value)
Each compact 2 was processed into JIS K 7218 A method b type and measured according to JIS K 7218 A method.
Also, the obtained limit PV value was evaluated based on the following evaluation criteria.

(Evaluation criteria)
○: limit PV value is 800 or more ×: limit PV value is less than 800

<Method for manufacturing molded body>
[Examples 1 to 2 and Comparative Examples 1 to 5]
(Production of polyamide compositions PA-a1 and PA-b1 to PA-b5)
Each polyamide composition was produced by the following method using each raw material component so as to have the composition shown in Table 1 below.
Polyamide A-1 was dried in a nitrogen stream to adjust the moisture content to about 0.2% by mass, and then used as a raw material for the polyamide composition.

A twin-screw extruder (ZSK-26MC: manufactured by Coperion GmbH (Germany)) was used as an apparatus for producing the polyamide composition.
The twin-screw extruder has an upstream feed port on the first barrel from the upstream side of the extruder, a downstream first feed port on the sixth barrel, and a downstream second feed port on the ninth barrel. had In the twin-screw extruder, the extruder length (lx)/screw diameter (dx) was 48, and the number of barrels was 12.
In the twin-screw extruder, the temperature from the upstream supply port to the die was set at 295° C., the screw rotation speed was set at 250 rpm, and the discharge rate was set at 25 kg/h.

As a specific manufacturing method using the above-described manufacturing apparatus, (A) polyamide is supplied from the upstream supply port of the twin-screw extruder, and other raw materials are supplied from the downstream first supply port of the twin-screw extruder. Then, the melt-kneaded product extruded from the die head was cooled in the form of a strand and pelletized to obtain pellets of each polyamide composition. The obtained polyamide composition pellets were dried in a nitrogen stream to reduce the water content in the polyamide composition to 500 ppm or less.

Table 1 below shows the physical properties and evaluation results of molded articles using the polyamide compositions obtained in Examples and Comparative Examples. In Table 1, "-" means that the compact did not break in the Charpy impact test.

From Table 1, polyamide compositions PA-a1 and PA-a2 (Examples 1 and 2) containing a polyamide, an olefin-based elastomer, and an ethylene-styrene graft copolymer are molded, and Rockwell The molded body with a hardness of 75 has a Charpy impact value of 8 or more, which is higher than the molded bodies C-b4 (Comparative Example 4) and C-b5 (Comparative Example 5) using the conventional slidability improver. was valued. In addition, the limit PV value is also 800 or more, and the molded products C-b4 (Comparative Example 4) and C-b5 (Comparative Example 5) using a conventional slidability improver with a limit PV value of less than 800 was improving.

On the other hand, molded bodies C-b1 to C-b2 obtained by molding polyamide compositions PA-b1 to PA-b2 containing a polyamide and an olefin elastomer and having a Rockwell hardness of 50 or less or 80 or more. In (Comparative Examples 1 and 2), the Charpy impact value was improved, but the limit PV value was less than 800, which was inferior.
Further, a molded body C-b3 obtained by molding a polyamide composition PA-b3 containing a polyamide and an ethylene-styrene graft copolymer and having a Rockwell hardness of 80 or more (Comparative Example 3), Both the Charpy impact value and critical PV value were poor.
Molded bodies C-b4 and C-, which are obtained by molding polyamide compositions PA-b4 and PA-b5 containing polyamide and a conventional slidability improver and have a Rockwell hardness of 80 or more. In b5 (Comparative Examples 4 and 5), both the Charpy impact value and limit PV value were inferior.

According to the polyamide composition of the present embodiment, it is possible to provide a polyamide composition from which a molded article having improved limit PV value and impact resistance can be obtained. The molded article of the present embodiment is obtained by molding the polyamide composition, and has improved limit PV value and impact resistance. According to the method of this embodiment, the limit PV value and impact resistance of the sliding member can be improved.

Claims (8)

a polyamide;
an olefinic elastomer; and
an ethylene-styrene graft copolymer;
A polyamide composition comprising: 2. The polyamide composition of claim 1, wherein said polyamide comprises at least one polyamide selected from the group consisting of polyamide 46 and polyamide 66. The polyamide composition according to claim 1 or 2, wherein the polyamide composition contains 5.00 parts by mass or more of the olefin elastomer with respect to 100.00 parts by mass of the polyamide. The polyamide composition comprises 5.00 parts by mass or more of the ethylene-styrene graft copolymer with respect to 100.00 parts by mass of the polyamide, the polyamide composition according to any one of claims 1 to 3. thing. Molded from the polyamide composition according to any one of claims 1 to 4,
A molded body having a Rockwell hardness of more than 50 and less than 80 as measured on the M scale in accordance with ISO 2039-2:1987. 6. The molded article according to claim 5, wherein the surface free energy determined by the theoretical formula of Owens and Wendt is 40 mJ/m< ² > or less. The molded article according to claim 5 or 6, which is a sliding member. A method for improving the limit PV value and impact resistance of a sliding member, comprising:
Obtaining a sliding member by molding a polyamide composition containing a polyamide, an olefin elastomer, and an ethylene-styrene graft copolymer,
A method according to ISO 2039-2, wherein the sliding member has a Rockwell hardness of more than 50 and less than 80 as measured on the M scale.